Shared Secret Key Generation Protocol in Wireless Networks Based on the Phase of MIMO Fading Channels

Much attention has recently been paid to methods of shared secret key generation that exploit the random characteristics of a fading channel, such as amplitude and phase of a received signal. Protocols based on the phase of a received signal are suitable in both static and dynamic environments, and they have a key generation rate (KGR) higher than that of protocols based on received signal strength. In addition, previous works have generally focused on key generation protocol for single-antenna (SISO) systems that mainly have not produced a significant KGR. This paper proposes a new key generation protocol with higher KGR. This is achieved by making received signal phase estimations on multiple-antenna (MIMO) systems because they have the potential to present more random variables in key generation compared to SISO systems. In addition, we present an extension of that protocol to generate a shared secret key between nodes in a network with a (N_T, N_R) MIMO structure. The simulation results show that the KGR in a (2, 2) and (3, 3) MIMO system is 4 and 9 times more than the KGR of a SISO system. Finally, the security of the proposed protocol is proven both in theory and by simulation.